1. Field of the Invention
The present invention relates, in general, to a plate-type fluorescent lamp and a display device having the same and, more particularly, to a plate-type fluorescent lamp and a display device having the same in which a dielectric layer is formed between a glass substrate and an electrode so as to reduce generating a pinhole.
2. Description of the Related Art
Recently, a flat panel display device, such as a liquid crystal display (“LCD”), a plasma display panel (“PDP”) or an organic light emitting diode (“OLED”), has been developed to replace a cathode ray tube (“CRT”).
The LCD includes an LCD panel having a thin film transistor (“TFT”) substrate, a color filter substrate and liquid crystals interposed between the two substrates. Since the LCD does not emit light by itself, the LCD includes a backlight unit disposed in a rear of the TFT substrate for providing light. A transmittance of the light from the backlight unit is controlled depending on an arrangement of the liquid crystals. The LCD panel and the backlight unit are contained in a chassis.
The backlight unit may either be an edge-type or a direct-type depending on a position of the light source part. The edge-type provides a light source like a cold cathode fluorescent lamp (“CCFL”), or the like, at a lateral side of a light guiding plate and a light concentrating sheet/diffusion sheet on the top of the light guiding plate. The direct-type provides a plurality of light sources behind the LCD panel and the light concentrating sheet/diffusion sheet between the light source and the LCD panel. However, the aforementioned backlight unit types are suitable for small and medium LCDs, such as those used in monitors and notebook computers, but are not suitable for large LCDs, such as those used in television monitors, due to problems of weight, thickness, electric power consumption, or the like.
A plate-type fluorescent lamp has been developed, as a light source suitable for a large LCD. A plate-type external electrode fluorescent lamp (“EEFL”) employs the principle of an EEFL in two-dimensions (2-D). The plate-type EEFL includes an upper substrate and a lower substrate, which form a light emitting space. Electrodes are formed on external surfaces of the upper substrate and the lower substrate. Both substrates include glass substrates, wherein the upper glass substrate is thinner than the lower glass substrate so as to simplify a manufacturing process of the plate-type EEFL, maintain a vacuum, assure a discharge space, and reduce weight.
When the plate-type EEFL is driven, the upper substrate has more capacity than in the lower substrate because the upper glass substrate is formed thinner than the lower glass substrate. Likewise, when an electric current flows into the upper substrate where capacity is largely formed, intense joule heating is generated and concentrated in the upper substrate.
The joule heating concentrated in the upper substrate makes the upper substrate rise in temperature, thereby generating a pinhole in the electrode and the upper glass substrate.